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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: KVPairIterator.html 878 2015-04-17 01:32:03Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.jsimpledb.kv;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.util.Arrays;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.util.Iterator;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import java.util.NoSuchElementException;<a name="line.12"></a>
<span class="sourceLineNo">013</span><a name="line.13"></a>
<span class="sourceLineNo">014</span>import org.jsimpledb.util.ByteUtil;<a name="line.14"></a>
<span class="sourceLineNo">015</span><a name="line.15"></a>
<span class="sourceLineNo">016</span>/**<a name="line.16"></a>
<span class="sourceLineNo">017</span> * An {@link Iterator} that iterates over all key/value pairs in a {@link KVStore} within a range of keys,<a name="line.17"></a>
<span class="sourceLineNo">018</span> * without using the {@link KVStore#getRange KVStore.getRange()} method. Therefore, it can be used to implement<a name="line.18"></a>
<span class="sourceLineNo">019</span> * {@link KVStore#getRange KVStore.getRange()} in {@link KVStore} implementations that don't natively support iteration.<a name="line.19"></a>
<span class="sourceLineNo">020</span> * Instances support forward or reverse iteration and {@link #remove Iterator.remove()}.<a name="line.20"></a>
<span class="sourceLineNo">021</span> *<a name="line.21"></a>
<span class="sourceLineNo">022</span> * &lt;p&gt;<a name="line.22"></a>
<span class="sourceLineNo">023</span> * The iteration is instead implemented using {@link KVStore#getAtLeast KVStore.getAtLeast()},<a name="line.23"></a>
<span class="sourceLineNo">024</span> * {@link KVStore#getAtMost KVStore.getAtMost()}, and {@link KVStore#remove KVStore.remove()}.<a name="line.24"></a>
<span class="sourceLineNo">025</span> * &lt;/p&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span> *<a name="line.26"></a>
<span class="sourceLineNo">027</span> * &lt;p&gt;&lt;b&gt;Repositioning&lt;/b&gt;&lt;/p&gt;<a name="line.27"></a>
<span class="sourceLineNo">028</span> *<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> * Instances support arbitrary repositioning via {@link #setNextTarget setNextTarget()}.<a name="line.30"></a>
<span class="sourceLineNo">031</span> * &lt;/p&gt;<a name="line.31"></a>
<span class="sourceLineNo">032</span> *<a name="line.32"></a>
<span class="sourceLineNo">033</span> * &lt;p&gt;&lt;b&gt;Key Restrictions&lt;/b&gt;&lt;/p&gt;<a name="line.33"></a>
<span class="sourceLineNo">034</span> *<a name="line.34"></a>
<span class="sourceLineNo">035</span> * &lt;p&gt;<a name="line.35"></a>
<span class="sourceLineNo">036</span> * Instances are configured with an (optional) {@link KeyRange} that restricts the iteration to the specified key range.<a name="line.36"></a>
<span class="sourceLineNo">037</span> * &lt;/p&gt;<a name="line.37"></a>
<span class="sourceLineNo">038</span> *<a name="line.38"></a>
<span class="sourceLineNo">039</span> * &lt;p&gt;<a name="line.39"></a>
<span class="sourceLineNo">040</span> * Instances also support filtering visible values using a {@link KeyFilter}.<a name="line.40"></a>
<span class="sourceLineNo">041</span> * To appear in the iteration, keys must both be in the {@link KeyRange} and pass the {@link KeyFilter}, if any.<a name="line.41"></a>
<span class="sourceLineNo">042</span> * &lt;/p&gt;<a name="line.42"></a>
<span class="sourceLineNo">043</span> *<a name="line.43"></a>
<span class="sourceLineNo">044</span> * &lt;p&gt;&lt;b&gt;Concurrent Modification&lt;/b&gt;&lt;/p&gt;<a name="line.44"></a>
<span class="sourceLineNo">045</span> *<a name="line.45"></a>
<span class="sourceLineNo">046</span> * &lt;p&gt;<a name="line.46"></a>
<span class="sourceLineNo">047</span> * Instances are thread safe, and always reflect the current state of the underlying {@link KVStore},<a name="line.47"></a>
<span class="sourceLineNo">048</span> * even if it is mutated concurrently.<a name="line.48"></a>
<span class="sourceLineNo">049</span> * &lt;/p&gt;<a name="line.49"></a>
<span class="sourceLineNo">050</span> */<a name="line.50"></a>
<span class="sourceLineNo">051</span>public class KVPairIterator implements Iterator&lt;KVPair&gt; {<a name="line.51"></a>
<span class="sourceLineNo">052</span><a name="line.52"></a>
<span class="sourceLineNo">053</span>    private final KVStore kv;<a name="line.53"></a>
<span class="sourceLineNo">054</span>    private final boolean reverse;<a name="line.54"></a>
<span class="sourceLineNo">055</span>    private final KeyRange keyRange;<a name="line.55"></a>
<span class="sourceLineNo">056</span>    private final KeyFilter keyFilter;<a name="line.56"></a>
<span class="sourceLineNo">057</span><a name="line.57"></a>
<span class="sourceLineNo">058</span>    private KVPair currPair;            // cached value to return from next()<a name="line.58"></a>
<span class="sourceLineNo">059</span>    private byte[] nextKey;             // next key lower/upper bound to go fetch, or null to start at the beginning<a name="line.59"></a>
<span class="sourceLineNo">060</span>    private byte[] removeKey;           // next key to remove if remove() invoked<a name="line.60"></a>
<span class="sourceLineNo">061</span>    private boolean finished;<a name="line.61"></a>
<span class="sourceLineNo">062</span><a name="line.62"></a>
<span class="sourceLineNo">063</span>// Constructors<a name="line.63"></a>
<span class="sourceLineNo">064</span><a name="line.64"></a>
<span class="sourceLineNo">065</span>    /**<a name="line.65"></a>
<span class="sourceLineNo">066</span>     * Convenience constructor for forward iteration over a specified range. Equivalent to:<a name="line.66"></a>
<span class="sourceLineNo">067</span>     *  &lt;blockquote&gt;&lt;code&gt;<a name="line.67"></a>
<span class="sourceLineNo">068</span>     *  KVPairIterator(kv, keyRange, null, false)<a name="line.68"></a>
<span class="sourceLineNo">069</span>     *  &lt;/code&gt;&lt;/blockquote&gt;<a name="line.69"></a>
<span class="sourceLineNo">070</span>     *<a name="line.70"></a>
<span class="sourceLineNo">071</span>     * @param kv underlying {@link KVStore}<a name="line.71"></a>
<span class="sourceLineNo">072</span>     * @param keyRange range restriction on visible keys, or null for none<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * @throws IllegalArgumentException if {@code kv} is null<a name="line.73"></a>
<span class="sourceLineNo">074</span>     */<a name="line.74"></a>
<span class="sourceLineNo">075</span>    public KVPairIterator(KVStore kv, KeyRange keyRange) {<a name="line.75"></a>
<span class="sourceLineNo">076</span>        this(kv, keyRange, null, false);<a name="line.76"></a>
<span class="sourceLineNo">077</span>    }<a name="line.77"></a>
<span class="sourceLineNo">078</span><a name="line.78"></a>
<span class="sourceLineNo">079</span>    /**<a name="line.79"></a>
<span class="sourceLineNo">080</span>     * Convenience constructor for forward iteration over all keys having a given prefix. Equivalent to:<a name="line.80"></a>
<span class="sourceLineNo">081</span>     *  &lt;blockquote&gt;&lt;code&gt;<a name="line.81"></a>
<span class="sourceLineNo">082</span>     *  KVPairIterator(kv, prefix, false)<a name="line.82"></a>
<span class="sourceLineNo">083</span>     *  &lt;/code&gt;&lt;/blockquote&gt;<a name="line.83"></a>
<span class="sourceLineNo">084</span>     *<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * @param kv underlying {@link KVStore}<a name="line.85"></a>
<span class="sourceLineNo">086</span>     * @param prefix range prefix<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * @throws IllegalArgumentException if any parameter is null<a name="line.87"></a>
<span class="sourceLineNo">088</span>     */<a name="line.88"></a>
<span class="sourceLineNo">089</span>    public KVPairIterator(KVStore kv, byte[] prefix) {<a name="line.89"></a>
<span class="sourceLineNo">090</span>        this(kv, prefix, false);<a name="line.90"></a>
<span class="sourceLineNo">091</span>    }<a name="line.91"></a>
<span class="sourceLineNo">092</span><a name="line.92"></a>
<span class="sourceLineNo">093</span>    /**<a name="line.93"></a>
<span class="sourceLineNo">094</span>     * Convenience constructor for iteration over all keys having a given prefix. Equivalent to:<a name="line.94"></a>
<span class="sourceLineNo">095</span>     *  &lt;blockquote&gt;&lt;code&gt;<a name="line.95"></a>
<span class="sourceLineNo">096</span>     *  KVPairIterator(kv, KeyRange.forPrefix(prefix), null, reverse)<a name="line.96"></a>
<span class="sourceLineNo">097</span>     *  &lt;/code&gt;&lt;/blockquote&gt;<a name="line.97"></a>
<span class="sourceLineNo">098</span>     *<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * @param kv underlying {@link KVStore}<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * @param prefix range prefix<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * @param reverse true to iterate in a reverse direction, false to iterate in a forward direction<a name="line.101"></a>
<span class="sourceLineNo">102</span>     * @throws IllegalArgumentException if any parameter is null<a name="line.102"></a>
<span class="sourceLineNo">103</span>     */<a name="line.103"></a>
<span class="sourceLineNo">104</span>    public KVPairIterator(KVStore kv, byte[] prefix, boolean reverse) {<a name="line.104"></a>
<span class="sourceLineNo">105</span>        this(kv, KeyRange.forPrefix(prefix), null, reverse);<a name="line.105"></a>
<span class="sourceLineNo">106</span>    }<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span>    /**<a name="line.108"></a>
<span class="sourceLineNo">109</span>     * Primary constructor.<a name="line.109"></a>
<span class="sourceLineNo">110</span>     *<a name="line.110"></a>
<span class="sourceLineNo">111</span>     * @param kv underlying {@link KVStore}<a name="line.111"></a>
<span class="sourceLineNo">112</span>     * @param keyRange range restriction on visible keys, or null for none<a name="line.112"></a>
<span class="sourceLineNo">113</span>     * @param keyFilter filter restriction on visible keys, or null for none<a name="line.113"></a>
<span class="sourceLineNo">114</span>     * @param reverse true to iterate in a reverse direction, false to iterate in a forward direction<a name="line.114"></a>
<span class="sourceLineNo">115</span>     * @throws IllegalArgumentException if {@code kv} is null<a name="line.115"></a>
<span class="sourceLineNo">116</span>     */<a name="line.116"></a>
<span class="sourceLineNo">117</span>    public KVPairIterator(KVStore kv, KeyRange keyRange, KeyFilter keyFilter, boolean reverse) {<a name="line.117"></a>
<span class="sourceLineNo">118</span>        if (kv == null)<a name="line.118"></a>
<span class="sourceLineNo">119</span>            throw new IllegalArgumentException("null kv");<a name="line.119"></a>
<span class="sourceLineNo">120</span>        this.kv = kv;<a name="line.120"></a>
<span class="sourceLineNo">121</span>        this.keyRange = keyRange;<a name="line.121"></a>
<span class="sourceLineNo">122</span>        this.keyFilter = keyFilter;<a name="line.122"></a>
<span class="sourceLineNo">123</span>        this.reverse = reverse;<a name="line.123"></a>
<span class="sourceLineNo">124</span>        this.setNextTarget(null);<a name="line.124"></a>
<span class="sourceLineNo">125</span>    }<a name="line.125"></a>
<span class="sourceLineNo">126</span><a name="line.126"></a>
<span class="sourceLineNo">127</span>// Methods<a name="line.127"></a>
<span class="sourceLineNo">128</span><a name="line.128"></a>
<span class="sourceLineNo">129</span>    /**<a name="line.129"></a>
<span class="sourceLineNo">130</span>     * Get the {@link KVStore} associated with this instance.<a name="line.130"></a>
<span class="sourceLineNo">131</span>     *<a name="line.131"></a>
<span class="sourceLineNo">132</span>     * @return this instance's transaction<a name="line.132"></a>
<span class="sourceLineNo">133</span>     */<a name="line.133"></a>
<span class="sourceLineNo">134</span>    public KVStore getKVStore() {<a name="line.134"></a>
<span class="sourceLineNo">135</span>        return this.kv;<a name="line.135"></a>
<span class="sourceLineNo">136</span>    }<a name="line.136"></a>
<span class="sourceLineNo">137</span><a name="line.137"></a>
<span class="sourceLineNo">138</span>    /**<a name="line.138"></a>
<span class="sourceLineNo">139</span>     * Get the {@link KeyRange} instance used to restrict the range of visible keys, if any.<a name="line.139"></a>
<span class="sourceLineNo">140</span>     *<a name="line.140"></a>
<span class="sourceLineNo">141</span>     * @return {@link KeyRange} over which this iterator iterates, or null if it iterates over all keys<a name="line.141"></a>
<span class="sourceLineNo">142</span>     */<a name="line.142"></a>
<span class="sourceLineNo">143</span>    public KeyRange getKeyRange() {<a name="line.143"></a>
<span class="sourceLineNo">144</span>        return this.keyRange;<a name="line.144"></a>
<span class="sourceLineNo">145</span>    }<a name="line.145"></a>
<span class="sourceLineNo">146</span><a name="line.146"></a>
<span class="sourceLineNo">147</span>    /**<a name="line.147"></a>
<span class="sourceLineNo">148</span>     * Get the {@link KeyFilter} instance used to filter visible keys, if any.<a name="line.148"></a>
<span class="sourceLineNo">149</span>     *<a name="line.149"></a>
<span class="sourceLineNo">150</span>     * @return {@link KeyFilter} in which all keys returned by this iterator must be contained, or null if keys are not filtered<a name="line.150"></a>
<span class="sourceLineNo">151</span>     */<a name="line.151"></a>
<span class="sourceLineNo">152</span>    public KeyFilter getKeyFilter() {<a name="line.152"></a>
<span class="sourceLineNo">153</span>        return this.keyFilter;<a name="line.153"></a>
<span class="sourceLineNo">154</span>    }<a name="line.154"></a>
<span class="sourceLineNo">155</span><a name="line.155"></a>
<span class="sourceLineNo">156</span>    /**<a name="line.156"></a>
<span class="sourceLineNo">157</span>     * Determine if this instance is going forward or backward.<a name="line.157"></a>
<span class="sourceLineNo">158</span>     *<a name="line.158"></a>
<span class="sourceLineNo">159</span>     * @return true if this instance is reversed<a name="line.159"></a>
<span class="sourceLineNo">160</span>     */<a name="line.160"></a>
<span class="sourceLineNo">161</span>    public boolean isReverse() {<a name="line.161"></a>
<span class="sourceLineNo">162</span>        return this.reverse;<a name="line.162"></a>
<span class="sourceLineNo">163</span>    }<a name="line.163"></a>
<span class="sourceLineNo">164</span><a name="line.164"></a>
<span class="sourceLineNo">165</span>    /**<a name="line.165"></a>
<span class="sourceLineNo">166</span>     * Determine if the given key would be visible in this instance. Tests the key against<a name="line.166"></a>
<span class="sourceLineNo">167</span>     * the configured {@link KeyRange} and/or {@link KeyFilter}, if any.<a name="line.167"></a>
<span class="sourceLineNo">168</span>     *<a name="line.168"></a>
<span class="sourceLineNo">169</span>     * @param key to test<a name="line.169"></a>
<span class="sourceLineNo">170</span>     * @return true if key is both in range and not filtered out<a name="line.170"></a>
<span class="sourceLineNo">171</span>     * @throws IllegalArgumentException if {@code key} is null<a name="line.171"></a>
<span class="sourceLineNo">172</span>     */<a name="line.172"></a>
<span class="sourceLineNo">173</span>    public boolean isVisible(byte[] key) {<a name="line.173"></a>
<span class="sourceLineNo">174</span>        if (key == null)<a name="line.174"></a>
<span class="sourceLineNo">175</span>            throw new IllegalArgumentException("null key");<a name="line.175"></a>
<span class="sourceLineNo">176</span>        return (this.keyRange == null || this.keyRange.contains(key))<a name="line.176"></a>
<span class="sourceLineNo">177</span>          &amp;&amp; (this.keyFilter == null || this.keyFilter.contains(key));<a name="line.177"></a>
<span class="sourceLineNo">178</span>    }<a name="line.178"></a>
<span class="sourceLineNo">179</span><a name="line.179"></a>
<span class="sourceLineNo">180</span>    /**<a name="line.180"></a>
<span class="sourceLineNo">181</span>     * Reposition this instance by setting the next "target" key.<a name="line.181"></a>
<span class="sourceLineNo">182</span>     *<a name="line.182"></a>
<span class="sourceLineNo">183</span>     * &lt;p&gt;<a name="line.183"></a>
<span class="sourceLineNo">184</span>     * The target key is the key we will use to find the next element via {@link KVStore#getAtLeast KVStore.getAtLeast()}<a name="line.184"></a>
<span class="sourceLineNo">185</span>     * or {@link KVStore#getAtMost KVStore.getAtMost()} if this is a reverse iterator. In the forward case, the target key is an<a name="line.185"></a>
<span class="sourceLineNo">186</span>     * inclusive lower bound on the next key, while in the reverse case it is an exclusive upper bound on the next key.<a name="line.186"></a>
<span class="sourceLineNo">187</span>     * &lt;/p&gt;<a name="line.187"></a>
<span class="sourceLineNo">188</span>     *<a name="line.188"></a>
<span class="sourceLineNo">189</span>     * &lt;p&gt;<a name="line.189"></a>
<span class="sourceLineNo">190</span>     * This method may be used to reposition an interator during iteration or restart an iterator that has been exhausted.<a name="line.190"></a>
<span class="sourceLineNo">191</span>     * Invoking this method does not affect the behavior of {@link #remove}, i.e., you can still {@link #remove} the previously<a name="line.191"></a>
<span class="sourceLineNo">192</span>     * returned element even if you have invoked this method since invoking {@link #next}.<a name="line.192"></a>
<span class="sourceLineNo">193</span>     * &lt;/p&gt;<a name="line.193"></a>
<span class="sourceLineNo">194</span>     *<a name="line.194"></a>
<span class="sourceLineNo">195</span>     * &lt;p&gt;<a name="line.195"></a>
<span class="sourceLineNo">196</span>     * A null {@code targetKey} means to reposition this instance at the beginning of the iteration.<a name="line.196"></a>
<span class="sourceLineNo">197</span>     * &lt;/p&gt;<a name="line.197"></a>
<span class="sourceLineNo">198</span>     *<a name="line.198"></a>
<span class="sourceLineNo">199</span>     * &lt;p&gt;<a name="line.199"></a>
<span class="sourceLineNo">200</span>     * This instance's configured {@link KeyRange} and {@link KeyFilter}, if any, still apply: if {@code targetKey} is not<a name="line.200"></a>
<span class="sourceLineNo">201</span>     * {@link #isVisible visible} to this instance, the next visible key after {@code targetKey} will be next in the iteration.<a name="line.201"></a>
<span class="sourceLineNo">202</span>     * &lt;/p&gt;<a name="line.202"></a>
<span class="sourceLineNo">203</span>     *<a name="line.203"></a>
<span class="sourceLineNo">204</span>     * @param targetKey next lower bound (exclusive) if going forward, or upper bound (exclusive) if going backward;<a name="line.204"></a>
<span class="sourceLineNo">205</span>     *  or null to restart this instance at the beginning of its iteration<a name="line.205"></a>
<span class="sourceLineNo">206</span>     */<a name="line.206"></a>
<span class="sourceLineNo">207</span>    public void setNextTarget(byte[] targetKey) {<a name="line.207"></a>
<span class="sourceLineNo">208</span><a name="line.208"></a>
<span class="sourceLineNo">209</span>        // Clone target key to avoid mutation<a name="line.209"></a>
<span class="sourceLineNo">210</span>        if (targetKey != null)<a name="line.210"></a>
<span class="sourceLineNo">211</span>            targetKey = targetKey.clone();<a name="line.211"></a>
<span class="sourceLineNo">212</span><a name="line.212"></a>
<span class="sourceLineNo">213</span>        // Ensure target is not prior to the beginning of the range<a name="line.213"></a>
<span class="sourceLineNo">214</span>        if (this.keyRange != null) {<a name="line.214"></a>
<span class="sourceLineNo">215</span>            if (this.reverse) {<a name="line.215"></a>
<span class="sourceLineNo">216</span>                final byte[] maxKey = this.keyRange.getMax();<a name="line.216"></a>
<span class="sourceLineNo">217</span>                if (maxKey != null &amp;&amp; (targetKey == null || ByteUtil.compare(targetKey, maxKey) &gt; 0))<a name="line.217"></a>
<span class="sourceLineNo">218</span>                    targetKey = maxKey;<a name="line.218"></a>
<span class="sourceLineNo">219</span>            } else {<a name="line.219"></a>
<span class="sourceLineNo">220</span>                final byte[] minKey = this.keyRange.getMin();<a name="line.220"></a>
<span class="sourceLineNo">221</span>                if (targetKey == null || ByteUtil.compare(targetKey, minKey) &lt; 0)<a name="line.221"></a>
<span class="sourceLineNo">222</span>                    targetKey = minKey;<a name="line.222"></a>
<span class="sourceLineNo">223</span>            }<a name="line.223"></a>
<span class="sourceLineNo">224</span>        }<a name="line.224"></a>
<span class="sourceLineNo">225</span><a name="line.225"></a>
<span class="sourceLineNo">226</span>        // Update state<a name="line.226"></a>
<span class="sourceLineNo">227</span>        synchronized (this) {<a name="line.227"></a>
<span class="sourceLineNo">228</span>            this.nextKey = targetKey;<a name="line.228"></a>
<span class="sourceLineNo">229</span>            this.finished = false;<a name="line.229"></a>
<span class="sourceLineNo">230</span>            this.currPair = null;<a name="line.230"></a>
<span class="sourceLineNo">231</span>        }<a name="line.231"></a>
<span class="sourceLineNo">232</span>    }<a name="line.232"></a>
<span class="sourceLineNo">233</span><a name="line.233"></a>
<span class="sourceLineNo">234</span>// Iterator<a name="line.234"></a>
<span class="sourceLineNo">235</span><a name="line.235"></a>
<span class="sourceLineNo">236</span>    @Override<a name="line.236"></a>
<span class="sourceLineNo">237</span>    public synchronized boolean hasNext() {<a name="line.237"></a>
<span class="sourceLineNo">238</span><a name="line.238"></a>
<span class="sourceLineNo">239</span>        // Already have next element?<a name="line.239"></a>
<span class="sourceLineNo">240</span>        if (this.currPair != null)<a name="line.240"></a>
<span class="sourceLineNo">241</span>            return true;<a name="line.241"></a>
<span class="sourceLineNo">242</span><a name="line.242"></a>
<span class="sourceLineNo">243</span>        // No more elements?<a name="line.243"></a>
<span class="sourceLineNo">244</span>        if (this.finished)<a name="line.244"></a>
<span class="sourceLineNo">245</span>            return false;<a name="line.245"></a>
<span class="sourceLineNo">246</span><a name="line.246"></a>
<span class="sourceLineNo">247</span>        // Find next element that is not filtered out by KeyRange<a name="line.247"></a>
<span class="sourceLineNo">248</span>        KVPair pair;<a name="line.248"></a>
<span class="sourceLineNo">249</span>        while (true) {<a name="line.249"></a>
<span class="sourceLineNo">250</span><a name="line.250"></a>
<span class="sourceLineNo">251</span>            // Find next key/value pair<a name="line.251"></a>
<span class="sourceLineNo">252</span>            if ((pair = this.reverse ? this.kv.getAtMost(this.nextKey) : this.kv.getAtLeast(this.nextKey)) == null) {<a name="line.252"></a>
<span class="sourceLineNo">253</span>                this.finished = true;<a name="line.253"></a>
<span class="sourceLineNo">254</span>                return false;<a name="line.254"></a>
<span class="sourceLineNo">255</span>            }<a name="line.255"></a>
<span class="sourceLineNo">256</span>            final byte[] key = pair.getKey();<a name="line.256"></a>
<span class="sourceLineNo">257</span><a name="line.257"></a>
<span class="sourceLineNo">258</span>            // Check key range<a name="line.258"></a>
<span class="sourceLineNo">259</span>            if (this.keyRange != null &amp;&amp; !this.keyRange.contains(key)) {<a name="line.259"></a>
<span class="sourceLineNo">260</span>                this.finished = true;<a name="line.260"></a>
<span class="sourceLineNo">261</span>                return false;<a name="line.261"></a>
<span class="sourceLineNo">262</span>            }<a name="line.262"></a>
<span class="sourceLineNo">263</span><a name="line.263"></a>
<span class="sourceLineNo">264</span>            // Check key filter; if going forward, avoid redundant call to seekHigher()<a name="line.264"></a>
<span class="sourceLineNo">265</span>            if (this.keyFilter == null)<a name="line.265"></a>
<span class="sourceLineNo">266</span>                break;<a name="line.266"></a>
<span class="sourceLineNo">267</span>            if (!this.reverse) {<a name="line.267"></a>
<span class="sourceLineNo">268</span>                final byte[] nextHigher = this.keyFilter.seekHigher(key);<a name="line.268"></a>
<span class="sourceLineNo">269</span>                if (nextHigher != null &amp;&amp; Arrays.equals(nextHigher, key))<a name="line.269"></a>
<span class="sourceLineNo">270</span>                    break;<a name="line.270"></a>
<span class="sourceLineNo">271</span>                this.nextKey = nextHigher;<a name="line.271"></a>
<span class="sourceLineNo">272</span>            } else {<a name="line.272"></a>
<span class="sourceLineNo">273</span>                if (this.keyFilter.contains(key))<a name="line.273"></a>
<span class="sourceLineNo">274</span>                    break;<a name="line.274"></a>
<span class="sourceLineNo">275</span>                this.nextKey = key.length &gt; 0 ? this.keyFilter.seekLower(key) : null;<a name="line.275"></a>
<span class="sourceLineNo">276</span>            }<a name="line.276"></a>
<span class="sourceLineNo">277</span><a name="line.277"></a>
<span class="sourceLineNo">278</span>            // We have skipped over the filtered-out key range, so try again if there is any left<a name="line.278"></a>
<span class="sourceLineNo">279</span>            if (this.nextKey == null) {<a name="line.279"></a>
<span class="sourceLineNo">280</span>                this.finished = true;<a name="line.280"></a>
<span class="sourceLineNo">281</span>                return false;<a name="line.281"></a>
<span class="sourceLineNo">282</span>            }<a name="line.282"></a>
<span class="sourceLineNo">283</span>        }<a name="line.283"></a>
<span class="sourceLineNo">284</span><a name="line.284"></a>
<span class="sourceLineNo">285</span>        // Save it (pre-fetch)<a name="line.285"></a>
<span class="sourceLineNo">286</span>        this.currPair = pair;<a name="line.286"></a>
<span class="sourceLineNo">287</span>        return true;<a name="line.287"></a>
<span class="sourceLineNo">288</span>    }<a name="line.288"></a>
<span class="sourceLineNo">289</span><a name="line.289"></a>
<span class="sourceLineNo">290</span>    @Override<a name="line.290"></a>
<span class="sourceLineNo">291</span>    public synchronized KVPair next() {<a name="line.291"></a>
<span class="sourceLineNo">292</span><a name="line.292"></a>
<span class="sourceLineNo">293</span>        // Check there is a next element<a name="line.293"></a>
<span class="sourceLineNo">294</span>        if (this.currPair == null &amp;&amp; !this.hasNext())<a name="line.294"></a>
<span class="sourceLineNo">295</span>            throw new NoSuchElementException();<a name="line.295"></a>
<span class="sourceLineNo">296</span><a name="line.296"></a>
<span class="sourceLineNo">297</span>        // Get next element<a name="line.297"></a>
<span class="sourceLineNo">298</span>        final KVPair pair = this.currPair;<a name="line.298"></a>
<span class="sourceLineNo">299</span>        final byte[] key = pair.getKey().clone();<a name="line.299"></a>
<span class="sourceLineNo">300</span>        this.removeKey = key;<a name="line.300"></a>
<span class="sourceLineNo">301</span><a name="line.301"></a>
<span class="sourceLineNo">302</span>        // Set up next advance<a name="line.302"></a>
<span class="sourceLineNo">303</span>        this.nextKey = this.reverse ? key : ByteUtil.getNextKey(key);<a name="line.303"></a>
<span class="sourceLineNo">304</span>        this.currPair = null;<a name="line.304"></a>
<span class="sourceLineNo">305</span><a name="line.305"></a>
<span class="sourceLineNo">306</span>        // Done<a name="line.306"></a>
<span class="sourceLineNo">307</span>        return pair;<a name="line.307"></a>
<span class="sourceLineNo">308</span>    }<a name="line.308"></a>
<span class="sourceLineNo">309</span><a name="line.309"></a>
<span class="sourceLineNo">310</span>    @Override<a name="line.310"></a>
<span class="sourceLineNo">311</span>    public void remove() {<a name="line.311"></a>
<span class="sourceLineNo">312</span>        final byte[] removeKeyCopy;<a name="line.312"></a>
<span class="sourceLineNo">313</span>        synchronized (this) {<a name="line.313"></a>
<span class="sourceLineNo">314</span>            if ((removeKeyCopy = this.removeKey) == null)<a name="line.314"></a>
<span class="sourceLineNo">315</span>                throw new IllegalStateException();<a name="line.315"></a>
<span class="sourceLineNo">316</span>            this.removeKey = null;<a name="line.316"></a>
<span class="sourceLineNo">317</span>        }<a name="line.317"></a>
<span class="sourceLineNo">318</span>        this.kv.remove(removeKeyCopy);<a name="line.318"></a>
<span class="sourceLineNo">319</span>    }<a name="line.319"></a>
<span class="sourceLineNo">320</span>}<a name="line.320"></a>
<span class="sourceLineNo">321</span><a name="line.321"></a>




























































</pre>
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